Assessment of organs-at-risk contouring practices in radiosurgery institutions around the world - The first initiative of the OAR Standardization Working Group.

Background And Purpose: This study was an initiative of the Organs-at-Risk Standardization Working Group for evaluating the current degree of variability in the clinical practice of contouring organs-at-risk (OAR) for radiosurgery planning.

Materials And Methods: Imaging datasets for typical lesions (cavernous sinus meningioma, vestibular schwannoma, pituitary adenoma) treated with Leksell Gamma Knife Perfexion were circulated to 12 centers. Observers were asked to contour the target and OARs as per their standard clinical practice.

Although Non-diagnostic Between Necrosis and Recurrence, FDG PET/CT Assists Management of Brain Tumours After Radiosurgery.

Aim: To re-evaluate the role of (18)F-fluoro-deoxy-D-glucose (FDG) positron emission tomography/ computer assisted tomography (PET/CT) co-registered with magnetic resonance imaging (MRI) in differentiating adverse radiation effect (ARE) from tumour recurrence after Gamma Knife radiosurgery of brain tumours.

Patients And Methods: Twenty-seven PET/CT studies co-registered with MRI were performed on 16 patients after radiosurgery, with 12/16 patients having multiple radiosurgery treatments. Long term follow-up was used for evaluation, with 3/16 patients being histopathologically confirmed.

Management of brain metastasis in a patient with advanced epithelial ovarian carcinoma by gamma-knife radiosurgery.

Introduction: Brain metastases from epithelial ovarian cancer (EOC) are rare events. We present a rare case of single ovarian cancer metastasis to the brain treated with gamma-knife radiosurgery (GKRS).

Case Outline: A 65-year-old woman with advanced EOC presented with severe neurologic symptoms.

Standardization of terminology in stereotactic radiosurgery: Report from the Standardization Committee of the International Leksell Gamma Knife Society: special topic.

Object: This report has been prepared to ensure more uniform reporting of Gamma Knife radiosurgery treatment parameters by identifying areas of controversy, confusion, or imprecision in terminology and recommending standards.

Methods: Several working group discussions supplemented by clarification via email allowed the elaboration of a series of provisional recommendations. These were also discussed in open session at the 16th International Leksell Gamma Knife Society Meeting in Sydney, Australia, in March 2012 and approved subject to certain revisions and the performance of an Internet vote for approval from the whole Society.

A simple and efficient methodology to improve geometric accuracy in gamma knife radiation surgery: implementation in multiple brain metastases.

Purpose: To propose, verify, and implement a simple and efficient methodology for the improvement of total geometric accuracy in multiple brain metastases gamma knife (GK) radiation surgery.

Methods And Materials: The proposed methodology exploits the directional dependence of magnetic resonance imaging (MRI)-related spatial distortions stemming from background field inhomogeneities, also known as sequence-dependent distortions, with respect to the read-gradient polarity during MRI acquisition. First, an extra MRI pulse sequence is acquired with the same imaging parameters as those used for routine patient imaging, aside from a reversal in the read-gradient polarity.

Malignant transformation in vestibular schwannoma: report of a single case, literature search, and debate.

Object: The significance of radiation in the induction of malignancy in vestibular schwannomas (VSs) after radiosurgery is unclear despite an increasing number of case reports. The authors describe a new case of verified malignant transformation in a vestibular schwannoma (MTVS) and provide a new evaluation of such cases previously reported in the literature.

Methods: A 46-year-old woman underwent subtotal resection of a right-sided VS in 2004.

Phase II study of neoadjuvant imatinib in glioblastoma: evaluation of clinical and molecular effects of the treatment.

Purpose: Phase I-II studies indicate that imatinib is active in glioblastoma multiforme. To better understand the molecular and clinical effects of imatinib in glioblastoma multiforme, we conducted a neoadjuvant study of imatinib with pretreatment and posttreatment biopsies.

Experimental Design: Patients underwent a computerized tomography-guided biopsy of their brain tumors.

Mechanical and dose delivery accuracy evaluation in radiosurgery using polymer gels.

The polymer gel-Magnetic Resonance Imaging (MRI) dosimetry technique was employed to evaluate the mechanical and dose delivery accuracy in Leksell gamma knife stereotactic radiosurgery for the treatment of multiple targets. Two different polymer gel dosimeter formulations that have been reported in the literature were prepared in-house. A plan for the treatment of four brain metastases (targets) was generated.